Flexible intermediate bulk container with induction control

Abstract

A method, apparatus and system is provided for both (1) decreasing electrostatic discharges to reduce the potential for incendiary discharges caused by electrostatic charges in flexible containers such as flexible intermediate bulk containers (FIBCs) and (2) decreasing the induction on isolated conductors nearby the container to reduce the potential for incendiary discharges from the isolated conductors.

What is new and desired to be protected by Letters Patent of the United States is: 
     
       1. A controlled-conductive flexible fabric container with a reduced energy of electrostatic discharge for use in a combustible environment, comprising: a woven fabric configured to form the flexible fabric container having one or more side walls; said fabric including a plurality of quasi-conductive fibers having corona discharge points, said fibers including one or more filaments, said filaments sized and shaped to effect: corona discharge at said corona discharge points while having resistance to avoid incendiary discharge at ends of said filaments and along the lengths of said filaments at a rate that results in incendiary type discharges in the combustible environment; and while grounded, there is sufficient charge dissipation within the container in order for the residual charge to be maintained below that required to cause potentials to be induced on nearby isolated conductors, said potentials sufficient to cause an incendiary discharge in the combustible environment. 
     
     
       2. A controlled-conductive flexible fabric container according to  claim 1 , wherein said filaments include a conductive core and an insulating sheath. 
     
     
       3. A controlled-conductive flexible fabric container according to  claim 1 , wherein the fabric container is a flexible intermediate bulk container. 
     
     
       4. A controlled-conductive flexible fabric container according to  claim 1 , wherein the container, while grounded, is being emptied or filled with highly charged particles. 
     
     
       5. A controlled-conductive flexible fabric container according to  claim 1 , wherein said woven fabric has an electrical resistivity to allow the flow of electricity through the fabric at a rate to discharge of between about four nanocoulombs to about fifteen nanocoulombs per individual discharge whenever the fabric is charged at greater than about negative ten thousand volts. 
     
     
       6. A controlled-conductive flexible fabric container according to  claim 1 , wherein said quasi-conductive fibers include multifilaments. 
     
     
       7. A controlled-conductive flexible fabric container according to  claim 1 , wherein said quasi-conductive fibers are sized and shaped to have a corona discharge threshold voltage at their ends in the range of about three to about four kilovolts and an end of a looped one of said sized and shaped quasi-conductive fibers has a corona discharge threshold voltage of about nine kilovolts. 
     
     
       8. A controlled-conductive flexible fabric container according to  claim 1 , wherein the combustible environment has a minimum ignition energy of 0.25 mJ. 
     
     
       9. A controlled-conductive flexible fabric container according to  claim 1 , wherein the combustible environment has a minimum ignition energy of 0.14 mJ. 
     
     
       10. A controlled-conductive flexible fabric container according to  claim 1 , wherein a combustible environment is a flammable vapor atmosphere, a dusty atmosphere, a combustible atmosphere, or an explosive atmosphere. 
     
     
       11. A controlled-conductive flexible fabric container according to  claim 1 , wherein said quasi-conductive fibers are woven into the fabric container. 
     
     
       12. A controlled-conductive flexible fabric container according to  claim 11 , wherein said quasi-conductive fibers are positioned about one to about four inches apart from one another. 
     
     
       13. A controlled-conductive flexible fabric container according to  claim 11 , wherein a surface of said walls is coated with an additive having antistatic or static dissipative properties. 
     
     
       14. A controlled-conductive flexible fabric container according to  claim 13 , wherein the coating antistatic or static dissipative material additive includes glycerol monostearate, Component X, or Component Y. 
     
     
       15. A controlled-conductive flexible fabric container according to  claim 14 , wherein the coating antistatic or static dissipative material additive includes greater than 4% to 12.5% Component X. 
     
     
       16. A controlled-conductive flexible fabric container according to  claim 14 , wherein the coating antistatic or static dissipative material additive includes to 2.5% to 5% Component Y, which is mixed with a compatibilizer. 
     
     
       17. A controlled-conductive flexible fabric container according to  claim 16 , wherein the compatibilizer is Component Z. 
     
     
       18. A controlled-conductive flexible fabric container according to  claim 17 , wherein Component Y is mixed with Component Z at a ratio of Component Y/Component Z between 5:1 to 1:2. 
     
     
       19. A controlled-conductive flexible fabric container according to  claim 18 , wherein the ratio of Component Y/Component Z is 2.5% Component Y/2% Component Z. 
     
     
       20. A controlled-conductive flexible fabric container according to  claim 18 , wherein the ratio of Component Y/Component Z is 5% Component Y/4% Component Z. 
     
     
       21. A controlled-conductive flexible fabric container according to  claim 14 , wherein the coating antistatic or static dissipative material additive includes 2.4% glycerol monostearate. 
     
     
       22. A controlled-conductive flexible fabric container according to  claim 21 , wherein the container is sewn with quasi-conductive yarns. 
     
     
       23. A controlled-conductive flexible fabric container according to  claim 21 , wherein the container is sewn with conductive yarns. 
     
     
       24. A controlled-conductive flexible fabric container according to  claim 21 , wherein the container fabric warp and/or well fibers includes 2.4% glycerol monostearate. 
     
     
       25. A controlled-conductive flexible fabric container according to  claim 24 , wherein the container is sewn with quasi-conductive yarns. 
     
     
       26. A controlled-conductive flexible container according to  claim 24 , wherein the container is sewn with conductive yarns. 
     
     
       27. A controlled-conductive flexible fabric container according to  claim 1 , further comprising at least one grounding tag. 
     
     
       28. A controlled-conductive flexible fabric container according to  claim 27 , wherein said grounding tag is made of fabric including quasi-conductive fibers. 
     
     
       29. A controlled-conductive flexible fabric container according to  claim 1 , wherein the container fabric warp and/or weft fibers includes an antistatic or static dissipative material as an additive. 
     
     
       30. A controlled-conductive flexible fabric container according to  claim 29 , wherein the fiber antistatic or static dissipative material additive includes glycerol monostearate, Component X, or Component Y. 
     
     
       31. A controlled-conductive flexible fabric container according to  claim 30 , wherein the fiber antistatic or static dissipative material additive includes 2.4% glycerol monostearate. 
     
     
       32. A controlled-conductive flexible fabric container according to  claim 30 , wherein the fiber antistatic or static dissipative material additive includes greater than 4% to 12.5% Component X. 
     
     
       33. A controlled-conductive flexible fabric container according to  claim 30  Y, wherein the fiber antistatic or static dissipative material additive includes 2.5% to 5% Component Y, which is mixed with a compatibilizer. 
     
     
       34. A controlled-conductive flexible fabric container according to  claim 33 , wherein the compatibilizer is Component Z. 
     
     
       35. A controlled-conductive flexible fabric container according to  claim 34 , wherein Component Y is mixed with Component Z at a ratio of Component Y/Component between 5:1 to 1:2. 
     
     
       36. A controlled-conductive flexible fabric container according to  claim 35 , wherein the ratio of Component Y/Component Z is 2.5% Component Y/2% Component Z. 
     
     
       37. A controlled-conductive flexible fabric container according to  claim 35 , wherein the ratio of Component Y/Component Z is 5% Component Y/4% Component Z. 
     
     
       38. A method for reducing the energy of electrostatic discharge in an ungrounded type flexible fabric container system suitable for use in a combustible environment, comprising the steps of: providing a woven fabric configured to form the flexible fabric container having side walls, a closed end and an open end; including within said woven fabric a plurality of quasi-conductive fibers, said fibers having one or more filaments that are sized and shaped to effect corona discharges at corona discharge points while having a resistance to avoid discharges at the ends and along the lengths of filaments at a rate that would result in an incendiary type of discharge in the combustible environment; and wherein the electrical resistivity of said woven fabric allows the flow of electricity through the fabric at a rate to discharge of below about one-hundred nanocoulombs per individual discharge whenever the fabric is charged at greater than about negative ten thousand volts, and including a coating with an anti-static agent on the fabric so that, while grounded, there is sufficient charge dissipation within the container in order for the residual charge to be maintained below that required to cause potentials to be induced on nearby isolated conductors, said potentials sufficient to cause an incendiary discharge in the combustible environment. 
     
     
       39. A method as in  claim 38  including the step of the container, while grounded, being emptied or filled with highly charged products. 
     
     
       40. A method as in  claim 38  wherein the combustible environment has a minimum ignition energy of 0.25 mJ. 
     
     
       41. A method as in  claim 38  wherein a combustible environment is a flammable vapor atmosphere, a dusty atmosphere, a combustible atmosphere, or an explosive atmosphere. 
     
     
       42. A method as in  claim 38  wherein said step of including quasi-conductive fibers adjusts the electrical resistivity of said woven fabric to allow the flow of electricity through the fabric at a rate to discharge of between about four nanocoulombs to about thirty nanocoulombs per individual discharge whenever the fabric is charged at greater than about negative ten thousand volts. 
     
     
       43. A method as in  claim 42  wherein said step of including quasi-conductive fibers comprises including multifilament fibers. 
     
     
       44. A method as in  claim 43  wherein said step of including multifilament fibers comprises including fibers having a conductive core and an insulating sheath. 
     
     
       45. A method as in  claim 42  wherein said step of including quasi-conductive fibers comprises the step of weaving the fibers into the fabric container. 
     
     
       46. A method as in  claim 45  wherein said step of including quasi-conductive fibers comprises positioning the fibers about one to about four inches apart from one another. 
     
     
       47. A method as in  claim 45  wherein the container coating includes an antistatic or static dissipative material as an additive. 
     
     
       48. A method as in  claim 47 , wherein the coating antistatic or static dissipative material additive includes glycerol monostearate, Component X, or Component Y. 
     
     
       49. A method as in  claim 48 , wherein the coating antistatic or static dissipative material additive includes greater than 4% to 12.5% Component X. 
     
     
       50. A method as in  claim 48 , wherein the coating antistatic or static dissipative material additive includes to 2.5% to 5% Component Y, which is mixed with a compatibilizer. 
     
     
       51. A method claim as in  claim 50 , wherein the compatibilizer is Component Z. 
     
     
       52. A method claim as in  claim 51 , wherein Component Y is mixed with Component Z at a ratio of Component Y/Component Z between 5:1 to 1:2. 
     
     
       53. A method claim as in  claim 52 , wherein the ratio of Component Y/Component Z is 2.5% Component Y/2% Component Z. 
     
     
       54. A method claim as in  claim 53 , wherein the ratio of Component Y/Component Z is 5% Component Y/4% Component Z. 
     
     
       55. A method as in  claim 48 , wherein the coating antistatic or static dissipative material additive includes 2.4% glycerol monostearate. 
     
     
       56. A method as in  claim 55 , wherein the container is sewn with quasi-conductive yarns. 
     
     
       57. A method as in  claim 55 , wherein the container is sewn with conductive yarns. 
     
     
       58. A method as in  claim 55 , wherein the container fabric warp and/or weft fibers includes 2.4% glycerol monostearate. 
     
     
       59. A method as in  claim 58 , wherein the container is sewn with quasi-conductive yarns. 
     
     
       60. A method as in  claim 59 , wherein the container is sewn with conductive yarns. 
     
     
       61. A method as in  claim 38 , wherein the container fabric warp and/or weft fibers includes an antistatic or static dissipative material as an additive. 
     
     
       62. A method as in  claim 61  wherein the fiber antistatic or static dissipative material additive includes glycerol monostearate, Component X, or Component Y. 
     
     
       63. A method as in  claim 62 , wherein the fiber antistatic or static dissipative material additive includes 2.4% glycerol monostearate. 
     
     
       64. A method as in  claim 62 , wherein the fiber antistatic or static dissipative material additive includes greater than 4% to 12.5% Component X. 
     
     
       65. A method as in  claim 62 , wherein the fiber antistatic or static dissipative material additive includes 2.5% to 5% Component Y, which is mixed with a compatibilizer. 
     
     
       66. A method as in  claim 65  wherein the compatibilizer is Component Z. 
     
     
       67. A method as in  claim 66 , wherein Component Y is mixed with Component Z at a ratio of Component Y/Component Z between 5:1 to 1:2. 
     
     
       68. A method as in  claim 67 , wherein the ratio of Component Y/Component Z is 2.5% Component Y/2% Component Z. 
     
     
       69. A method as in  claim 67 , wherein the ratio of Component Y/Component Z is 5% Component Y/4% Component Z. 
     
     
       70. A woven fabric for use in a controlled-conductive flexible container, the fabric comprising: interwoven warp and weft fibers; a coating of a compound having antistatic properties applied to cover a surface of said fabric; and a plurality of quasi-conductive fibers having corona discharge points, said fibers including one or more filaments, said filaments sized and shaped to effect: corona discharge at said corona discharge points while having resistance to avoid discharge at ends of said filaments and along the lengths of said filaments at a rate that results in incendiary type discharges in a combustible environment, wherein the fabric is configured such that the container, while grounded, has sufficient charge dissipation within the container in order for the residual charge to be maintained below that required to cause potentials to be induced on nearby isolated conductors, said potentials sufficient to cause an incendiary discharge in the combustible environment. 
     
     
       71. A fabric according to  claim 70 , wherein said woven fabric has an electrical resistivity to allow the flow of electricity through the fabric at a rate to discharge of between about four nanocoulombs to about fifteen nanocoulombs per individual discharge whenever the fabric is charged at greater than about negative ten thousand volts. 
     
     
       72. A fabric according to  claim 70 , wherein said quasi-conductive fibers are woven into the fabric. 
     
     
       73. A fabric according to  claim 72 , wherein said quasi-conductive fibers are positioned about one to about four inches apart from one another. 
     
     
       74. A fabric according to  claim 73 , wherein said quasi-conductive fibers include multifilaments. 
     
     
       75. A fabric according to  claim 74 , wherein said filaments include a conductive core and an insulating sheath. 
     
     
       76. A fabric according to  claim 72 , wherein the coating antistatic or static dissipative material additive includes glycerol monostearate, Component X, or Component Y. 
     
     
       77. A fabric according to  claim 76 , wherein the coating antistatic or static dissipative material additive includes greater than 4% to 12.5% Component X. 
     
     
       78. A fabric according to  claim 76 , wherein the coating antistatic or static dissipative material additive includes to 2.5% to 5% Component Y, which is mixed with a compatibilizer. 
     
     
       79. A fabric according to  claim 78 , wherein the compatibilizer is Component Z. 
     
     
       80. A fabric according to  claim 79 , wherein Component Y is mixed with Component Z at a ratio of Component Y/Component Z between 5:1 to 1:2. 
     
     
       81. A fabric according to  claim 80 , wherein the ratio of Component Y/Component Z is 2.5% Component Y/2% Component Z. 
     
     
       82. A fabric according to  claim 81  wherein the ratio of Component Y/Component Z is 5% Component Y/4% Component Z. 
     
     
       83. A fabric according to  claim 76 , wherein the coating antistatic or static dissipative material additive includes 2.4% glycerol monostearate. 
     
     
       84. A fabric according to  claim 83 , wherein the container is sewn with quasi-conductive yarns. 
     
     
       85. A fabric according to  claim 83 , wherein the container is sewn with conductive yarns. 
     
     
       86. A controlled-conductive flexible fabric container according to  claim 83 , wherein the container fabric warp and/or weft fibers includes 2.4% glycerol monostearate. 
     
     
       87. A controlled-conductive flexible fabric container according to  claim 86 , wherein the container is sewn with quasi-conductive yarns. 
     
     
       88. A controlled-conductive flexible container according to  claim 87 , wherein the container is sewn with conductive yarns.